Williams & Connolly, which was started in 1967 by the legendary trial lawyer Edward Bennett Williams, is known mainly for its litigation prowess and Beltway insider credentials. The firm represented Oliver North in the Iran-Contra scandal and President Bill Clinton in his impeachment trial.

But Williams & Connolly has also carved out a niche representing talent across the entertainment industry. It’s an unusual business for a corporate law firm, but Williams & Connolly has always had an iconoclastic streak. While other elite Washington firms, like Hogan Lovells, have grown into global mega-firms, Williams & Connolly, at 250 lawyers, has remained relatively small.

Typically, a talent agency like William Morris Endeavor or Creative Artists Agency represents athletes and authors. These agencies charge their clients a percentage of their income — normally 10 percent to 15 percent — as a fee. But Mr. Barnett and Mr. Tanner undercut these agencies by not charging commission and instead billing by the hour.

Mr. Barnett, a corporate lawyer by training, has for nearly three decades become the go-to literary agent for government officials and D.C. journalists. He has represented President Barack Obama, George W. Bush and Bill Clinton.

His assignment to take on Ms. Curry’s negotiations with NBC falls into his other “side job” of representing television journalists. Mr. Barnett, who is married to Rita Braver of CBS News, recently advised Christiane Amanpour during her exit from ABC News’s “This Week.”

Mr. Tanner, the basketball agent, appears to have taken a page out of Mr. Barnett’s playbook. He joined Williams & Connolly in 1997 after spending four years as a corporate lawyer at Skadden, Arps, Slate, Meagher & Flom. He moved to Williams & Connolly to work under Lon Babby, a partner at the firm who was building a practice representing professional basketball players. In 2010, Mr. Babby left the firm to become president of the Phoenix Suns.

Representing Mr. Lin is a coup for Mr. Tanner. After his breakout season and the “Linsanity” phenomenon, Mr. Lin is expected to command more than $5 million a year, according to The New York Times’s Howard Beck.

Williams & Connolly has deep connections to the world of professional sports. Larry Lucchino, a former partner, is the chief executive of the Boston Red Sox. And Mr. Williams, the firm’s founder, was the owner of the Baltimore Orioles and served as president of the Washington Redskins for 20 years.